Heart disease, specifically coronary artery disease, is a major cause of death, disability, and healthcare expense in the United States and other industrialized countries. A number of methods and devices for treating coronary heart disease have been developed, some of which are specifically designed to treat the complications resulting from atherosclerosis and other forms of coronary arterial narrowing.
One method for treating such conditions is percutaneous transluminal coronary angioplasty (PTCA). During PTCA, a balloon catheter device is inflated to dilate a stenotic blood vessel. The stenosis may be the result of a lesion such as a plaque or thrombus. When inflated, the pressurized balloon exerts a compressive force on the lesion, thereby increasing the inner diameter of the affected vessel. The increased interior vessel diameter facilitates improved blood flow. Soon after the procedure, however, a significant proportion of treated vessels restenose.
To prevent restenosis, stents, constructed of a metal or polymer and generally cylindrical in shape and hollow, are implanted within the vessel to maintain lumen size. The stent acts as a scaffold to support the lumen in an open position. Configurations of stents include a cylindrical sleeve defined by a mesh, interconnected stents, or like segments. Exemplary stents are disclosed in U.S. Pat. No. 5,292,331 to Boneau, U.S. Pat. No. 6,090,127 to Globerman, U.S. Pat. No. 5,133,732 to Wiktor, U.S. Pat. No. 4,739,762 to Palmaz and U.S. Pat. No. 5,421,955 to Lau.
Stent insertion may cause undesirable reactions such as inflammation, infection, thrombosis, and proliferation of cell growth that occludes the passageway. To assist in preventing these conditions, stents have been used with coatings to deliver drugs or other therapeutic agents at the site of the stent.
The efficacy of a stent may be reduced when repairing a vessel affected by stenosis at the point at which the vessel originates, branching off from an adjoining vessel. This point of origin is referred to as the ostium of the vessel. A lesion located at this point is termed an ostial lesion.
To repair an ostial lesion, a stent must cover the entire affected area without occluding blood flow in the adjoining vessel. However, when a conventional stent overlies the entire ostium of the affected vessel, it may also extend into the adjoining vessel, occluding blood flow to some degree. Furthermore, when the stent extends into the adjoining vessel, the stent may block access to portions of the adjoining vessel that require further intervention.
U.S. Pat. No. 5,749,890 to Shaknovich discloses a method and system for stent placement in an ostial lesion that ensures the stent does not extend into the adjoining vessel. However, the method and system do not ensure coverage of the affected area where it extends into the junction with the adjoining vessel. U.S. Pat. No. 5,607,444 to Lam describes an ostial stent having a flaring portion that provides coverage of at least a portion of a lesion at the junction of the two vessels. This invention, however, describes no means for actively conforming the stent to the shape of the specific ostium being treated.
Therefore, it would be desirable to have a method and system for treating an ostium of a side-branch vessel that overcomes the aforementioned and other disadvantages.